A quantum-theoretical approach to the phenomenon of directed mutations in bacteria (hypothesis)

摘要

The Darwinian paradigm of biological evolution is based on the independence of genetic variations from selection which occurs afterwards. However, according to the phenomenon of directed mutations, some genetic variations occur mostly when the conditions favorable for their growth are created. I propose that the explanation of this phenomenon should not rely on any special 'mechanism' for the appearance of directed mutations, but rather should be based on the principles of quantum theory. I consider a physical model of adaptation whereby a polarized photon, passing through a polarizer, changes its polarization according to the angle of the polarizer. This adaptation occurs by selection of the 'fitted' polarized state which exists as a component of superposition in the initial state of the photon. However, since the same state of the incoming photon should be decomposed differently depending on the angle of the polarizer, in this case the set of variations subjected to selection depends upon the selective conditions themselves. This reveals the crucial difference between this model of adaptation and canonical Darwinian selection. Based on this analogy, the capacity of a cell to grow in particular conditions is considered an observable of the cell; the plating experiments are interpreted as measurement of this observable. The only nontrivial suggestion of the paper states that the cell, analogously to the polarized photon, may be in a state of superposition of eigenfunctions of the operator which represents this observable, and with some probability can appear as a mutant upon the measurement. Alternative growth conditions correspond to the decomposition of the same state vector into a different superposition, consistent with measurement of a different observable and appearance of different mutants. Thus, consistent with the suggested analogy, directed mutations are explained as a result of random choice from the set of outcomes determined by the environment. (C) 1997 Elsevier Science Ireland Ltd.